1. Field of the Invention
The present invention relates to a product, and a method for making the product, that releases a volatile substance into the environment in a controlled manner. In particular, this invention relates to a method of making a product that contains the volatile substance for controlled release over an extended time while preventing it from spilling or oozing in liquid form.
Many consumer products such as room deodorizers, insecticides, germicides, fragrances and the like are volatile and may be released and dispersed in an area to be treated merely by being exposed therein. Devices for dispensing these products are also available in many forms such as liquid and wick systems, blotter systems and gel systems. However, the volatile substances may be subject to spillage, oozing or waste in each of these systems. Furthermore, methods of packaging such substances are subject to limitations imposed by the package itself. For example, liquids that are sold in bottles, cans or other rigid containers require relatively complex and expensive bottling or canning apparatus.
2. Description of the Prior Art
Various devices and methods for containing a volatile substance and for controlling the release of vapor from the substance are presently known. U.S. Patent application Ser. No. 731,300 (Sullivan & Meetze), assigned to the assignee of the present invention, discloses a device for releasing a volatile substance that includes a reservoir of substance-adsorbent material encapsulated in an envelope, at least a portion of which comprises a permeable material having porosity at least equal to ultramicroporosity. The permeable envelope portion has a greater affinity for the substance than does the reservoir material. The remainder of the envelope comprises a material impermeable to the substance. Accordingly, the substance permeates through the permeable envelope portion to be released in vapor form into the environment. The method of the present invention can be used to make devices of this type.
Other devices for releasing a volatile substance are disclosed in U.S. Pat. Nos. 3,216,882 (Feldt et al.); 3,770,199 (Hoek et al.) and in U.S. Pat. No. 4,035,451 (Tringali), assigned to the assignee of the present invention.
Methods and apparatus for making envelopes which are filled with various substances are also known. For example, U.S. Pat. Nos. 2,616,232 (Meyer); 2,970,414 (Rohdin); 3,007,848 (Stroop); 3,069,273 (Wayne); 3,495,992 (De For); and 3,978,636 (Clancy) disclose apparatus and methods for producing packages from two layers of endless film material from two supplies. The product that is held by the package may be added before or after final package formation and is completely encapsulated thereby. However, the methods of packaging a solid or gelatinous substance, such as those disclosed in the Stroop and Clancy Patents, separate the substance into discreet quantities so that the enveloping materials may be sealed without interference therefrom. Accordingly, the substance should be accurately positioned between the enveloping materials to prevent poor sealing.
U.S. Pat. No. 3,391,047 (Kopp) discloses an apparatus for manufacturing a dual compartment sachet. Three layers of a thin film are welded together to form the two compartments which may be filled with different materials.
U.S. Pat. No. 3,070,225 (Schwartz) discloses a package for a bandage and a method of making the package.
None of the patents noted above disclose a method for making a product which holds and dispenses a volatile product, nor do any disclose a method of making a package comprised of a backing material, a reservoir material and a permeable material that automatically seals the reservoir material about a closed periphery. Moreover, no disclosure is made of a process for making a device, that dispenses a volatile product in a manner that controls the rate at which the product is volatilized.